“That didn’t get a lot of applause,” firebrand Rep. Steve King (R-Iowa) observed with a tight smile.

“Some things are too funny to comment on,” a laughing Newt Gingrich commented as he walked into the conference to give his own speech.

Romney’s address won repeated applause. He outlined his conservative credentials, both in his public and private life, and offered a strong indictment of President Barack Obama. But by going off-script to use an awkward modifier that no movement conservative would ever affix to themselves, he made clear why, despite vast advantages in money and organization, he’s still struggling to win the trust of a party base needed to secure the GOP presidential nomination. He’s just not a natural fit.

Success at CPAC is hardly a perfect indicator for how a candidate will perform with the Republican electorate. Romney knows this well, having captured the straw poll here in the past only to lose the nomination to a candidate, John McCain, who was booed when he addressed the conference just weeks before securing the GOP nod.

Yet Romney’s trio of losses Tuesday and his all-out effort to woo the base here — he used some variation of “conservative” 25 separate times in his speech — underscores the degree to which the party has shifted in the four years since McCain captured the nomination.

The old nominating game standbys, the notions of inevitability and success begetting success, have proven irrelevant in 2012. Romney rolled in Florida and cruised in Nevada — and then, without an aggressive campaign, had nothing to show for it in Minnesota, Missouri and Colorado. This election has proven momentum-proof to date.

Romney’s still the smart-money favorite to become the Republican standard-bearer, but it’s increasingly clear that he’s going to have to make a more compelling case to conservatives to ensure victory.

The central question now looming over the race is, to borrow a phrase, just how severely the party has moved right. How profound is the scale of resistance to Romney?

“You’ve got to have a trust factor, you’ve got to make sure he’s genuine,” said Rep. Allen West (R-Fla.), a leading tea-party freshman, in attempting to explain conservative unease with the front-runner. “And with Romneycare there are a lot of similarities with the Affordable Care Act.”

The depth of Romney’s challenge with the base was demonstrated by what took place after his speech. After the candidate made no mention of his signature accomplishment as Massachusetts governor, health care reform, a panel took the stage and devoted significant time to fulminating against the individual mandate.